Gauss' Law as a derivative of the electromagnetic field tensor

In summary, the content discusses a problem involving proving the equation \nabla \bullet E =4 \pi \rho from \partial_{\beta}F^{\alpha \beta}=4 \pi J^{\alpha}, where J^{\alpha}=(\rho, J^{1}, J^{2}, J^{3}) and F_{\alpha \beta} is given in matrix form. The solution involves raising the indices and solving for \partial_{i}E^{i}. The confusion over a negative sign was resolved.
  • #1
mjordan2nd
177
1

Homework Statement



Prove [tex]\nabla \bullet E =4 \pi \rho[/tex] from [tex]\partial_{\beta}F^{\alpha \beta}=4 \pi J^{\alpha}[/tex] where [tex]J^{\alpha}=(\rho, J^{1}, J^{2}, J^{3})[/tex].

Homework Equations



We are given that [tex]F_{\alpha \beta}[/tex] is

0~~~~E_x~~~E_y~~~E_z
-E_x~~~0~~~~-B_z~~B_y
-E_y~~B_z~~~~0~~~-B_x
-E_z~~-B_y~~~B_x~~~0

(Sorry, don't know how to do matrices.)

Raising the indices I should get

0~~~-E_x~~-E_y~~-E_z
E_x~~~0~~~~-B_z~~B_y
E_y~~B_z~~~~0~~~-B_x
E_z~~-B_y~~~B_x~~~0

The Attempt at a Solution



[tex]\partial_{\beta}F^{\alpha \beta}=4 \pi J^{\alpha}=>-\partial_{i}F^{0i}=\rho=-\partial_{i}E_{i}[/tex]. I don't know why I keep getting that pesky negative sign! Can anyone point me in the right direction?
 
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  • #2
For whatever reason I can't edit the latex, but it should say it as follows:

(interestingly enough after this post the op corrected itself)

Homework Statement



Prove [tex]\nabla \bullet E =4 \pi \rho[/tex] from [tex]\partial_{\beta}F^{\alpha \beta}=4 \pi J^{\alpha}[/tex] where [tex]J^{\alpha}=(\rho, J^{1}, J^{2}, J^{3})[/tex].

Homework Equations



We are given that [tex]F_{\alpha \beta}[/tex] is

0~~~~E_x~~~E_y~~~E_z
-E_x~~~0~~~~-B_z~~B_y
-E_y~~B_z~~~~0~~~-B_x
-E_z~~-B_y~~~B_x~~~0

(Sorry, don't know how to do matrices.)

Raising the indices I should get

0~~~-E_x~~-E_y~~-E_z
E_x~~~0~~~~-B_z~~B_y
E_y~~B_z~~~~0~~~-B_x
E_z~~-B_y~~~B_x~~~0

The Attempt at a Solution



[tex]\partial_{\beta}F^{\alpha \beta}=4 \pi J^{\alpha}=>-\partial_{i}F^{0i}=\rho=-\partial_{i}E^{i}[/tex]. I don't know why I keep getting that pesky negative sign! Can anyone point me in the right direction?
 
  • #3
Bleh, never mind, I got it. Just got the rows and columns confused somehow... Thanks anyway, sorry for wasting your time.
 

Related to Gauss' Law as a derivative of the electromagnetic field tensor

1. What is Gauss' Law as a derivative of the electromagnetic field tensor?

Gauss' Law is a fundamental law of electromagnetism that describes the relationship between electric charges and the electric field. It states that the electric flux through any closed surface is equal to the total charge enclosed by that surface. As a derivative of the electromagnetic field tensor, it provides a mathematical representation of the law in terms of the electric and magnetic fields.

2. How does Gauss' Law relate to Maxwell's equations?

Gauss' Law is one of the four Maxwell's equations, which are a set of fundamental equations that describe the behavior of electric and magnetic fields. Specifically, Gauss' Law relates to the first of Maxwell's equations, known as Gauss' Law for electric fields, which states that the divergence of the electric field is proportional to the charge density at a given point.

3. What is the significance of Gauss' Law as a derivative of the electromagnetic field tensor?

Gauss' Law as a derivative of the electromagnetic field tensor provides a more general and concise expression of the law, as it takes into account both electric and magnetic fields. This allows for a more comprehensive understanding of the relationship between electric charges and the electromagnetic fields they produce.

4. How is Gauss' Law used in practical applications?

Gauss' Law is used in a variety of practical applications, such as in the design and analysis of electrical circuits, electromagnetic devices, and antennas. It is also used in the study of electromagnetic waves and their propagation through different media.

5. Can Gauss' Law be applied to non-stationary electric fields?

Yes, Gauss' Law can be applied to non-stationary electric fields by considering the time-varying charge density and electric field. This leads to the modified version of Gauss' Law known as the Gauss' Law for time-varying fields, which is an important concept in the study of electromagnetic radiation and electromagnetic waves.

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